The present invention generally relates to a fluid mixer and, in particular, relates to one such fluid mixer having a plurality of fluid inlet conduits terminating proximate a first surface of a chamber such that fluids exiting the conduits impinge upon a single location of the first surface.
As used herein the term fluid and the derivatives thereof will be taken to include liquids, gases supercritical fluids and generally all flow compatible areas defined by a typical thermodynamic state diagram. However, for the sake of consistency and by way of example only, the following description will primarily refer to gases.
There are many instances, such as the precise plasma etching of a substrate, wherein the composition of a gas is required to be highly uniform over an extended period of time. In most instances, however, the gas is a mixture of a number of different gases. Thus, a gas mixer is frequently introduced into the gas delivery system. However, it has been found that most conventional gas mixers do not thoroughly mix gases. Typically, these conventional gas mixers can be categorized as either the manifold type or the expansion chamber type.
In general, the manifold type of gas mixer usually include a straight tube having a plurality of inputs and a single output located distal the inputs. In most manifold designs, the straight tube has a sealed end(s) to force the gases toward the output. The primary disadvantage of the manifold gas mixer is that for gases having different flow velocities, hence, different densities for constant tube diameters, the flow in the manifold may readily become stratified rather than mixed.
The expansion chamber type of gas mixer usually includes a plurality of inlet conduits on one wall thereof and a single outlet conduit on the opposing wall. The principle of the expansion chamber gas mixer is to allow the incoming gases to expand such that the forward flow velocity of the incoming gas is substantially reduced, preferably to close to zero forward velocity. In this manner the incoming gases expand and simultaneously mix. However, this type of gas mixer is disadvantageous since the actual mixing of the gases is substantially uncontrolled.
Consequently, it will be readily understood that there is a great need and desire for a fluid mixer that reliably and controllably mixes a plurality of fluids such that the output mixture thereof is uniform.